<svg xmlns="http://www.w3.org/2000/svg"
     xmlns:xlink="http://www.w3.org/1999/xlink"
     width="100" height="100">
  <!-- This blue rect should always be covered up by the <image>: -->
  <circle cx="50" cy="50" r="50" fill="blue"/>
  <image width="100" height="100"
         xlink:href="%3D%3D"/>
</svg>
